1. Field of the Invention
The present invention pertains to a metal finishing process and more particularly, to a metal finishing process which prevents the chemical reactions known as "leakout" and "outgassing".
2. Problem to be Solved
Zinc die casting are widely used for the production of commodities including plumbing fixtures, door handles, toys and automotive parts. It has been found that when the adhesion between a zinc die cast component and a brass or bronze electroplate is insufficient, reactions known as "leakout" and "outgassing" occur.
Outgassing is the escape of atmospheric gases, such as air, trapped in the pores of the zinc substrate, between the substrate and the plating, and within the pores of the plating. The gases typically escape during the curing process of the powdered coating which is applied to the final plated surface. As the component is heated to cure the powdered coating, the gases escape from the pores in the substrate through the pores in the plating and emerge into the atmosphere. Outgassing manifests itself as bubbles in the clear powder coating formed by the penetration of the gases in the powder coating as the powder coating cures.
Leakout is a discoloration on the surface of the electroplating and is caused by chemicals, such as cyanide, entrapped in the pores of the plated surface that react with atmospheric moisture. Leakout results in a dark discoloration of the electroplate. Leakout is especially prevalent in brass or bronze plated substrates because the brass and bronze plating processes are typically available in a cyanide chemistry.
One conventional method requires application of lacquer to the electroplate surface. However, it has been found that lacquer does not offer an adequate moisture barrier to prevent leakout and outgassing.
Therefore, it is an object of the invention to provide a new and improved metal finishing process that prevents the chemical reaction known as leakout.
It is another object of the present invention to provide a new and improved metal finishing process that prevents the chemical reaction known as outgassing.
It is another object of the present invention to provide a new and improved metal finishing process for electroplating base metal substrates with brass or bronze that prevents the chemical reaction known as leakout.
It is another object of the present invention to provide a new and improved metal finishing process for electroplating base metal substrates with brass or bronze that prevents the chemical reaction known as outgassing.
It is a further object of the invention to provide a new and improved zinc die cast component electroplated with brass or bronze that does not exhibit the chemical reaction known as leakout.
It is a further object of the invention to provide a new and improved zinc die cast component electroplated with brass or bronze that does not exhibit the chemical reaction known as outgassing.
It is a feature of the invention to polish and buff the surface of the base metal substrate to substantially remove coarse surfaces, pores, cavities and minor indentations.
A further feature of the present invention to is electroplate a copper layer over the substrate surface to provide a substantially uniform surface upon which is plated a layer of brass or bronze.
It is another feature of the invention to electrostatically apply a clear epoxy coating to the final electroplated surface of the component.
An advantage of the present invention is improved adhesion between the base metal substrate and the copper plating which inhibits the occurrence of leakout and outgassing when the temperature of the substrate is elevated.